The Sun's Annual Circuit — North and South
On the flat Earth, the sun does not orbit in a fixed circle. Over the course of a year (approximately 365 days), it spirals outward from the Tropic of Cancer (its northernmost circuit) at the June solstice, then spirals inward (southward) toward the Tropic of Capricorn by the December solstice, then returns northward again. Each daily circuit is slightly further from or closer to the North Pole depending on where in the annual cycle it falls.
Summer in any region is when the sun's daily circuit is closest to that region — meaning the sun passes more directly overhead, spends more hours above the relevant portion of the plane, and delivers more concentrated (shorter path through atmosphere, higher angle) heat and light. Winter is when the sun's circuit is furthest from a given region — the sun passes at a lower angle, spends fewer hours above the region's dawn-to-dusk arc, and delivers less concentrated illumination.
The Tropics — Defined by the Sun's Circuit Limits
The Tropic of Cancer (23.5° North latitude) and Tropic of Capricorn (23.5° South latitude) are the geographic circles on Earth's surface where the sun is directly overhead at the solstices. These are not arbitrary lines — they define the northernmost and southernmost extent of the sun's annual circuit on the flat Earth plane. At the June solstice, the sun's circuit is directly above the Tropic of Cancer ring on the flat Earth disc. At the December solstice, it is directly above the Tropic of Capricorn ring.
When the sun's circuit is closest to a region (summer), the arc of its path that is visible from that region — the portion above that observer's local horizon — is larger. The sun rises earlier and sets later because it is traversing a portion of its flat-earth circuit that passes deeper over that region. In winter, the sun's circuit is further away, its traversal above a given location's visible arc is shorter, and it "rises" later and "sets" earlier. No axial tilt required — geometry of a local sun over a flat plane explains it precisely.
The Equinoxes and Solstices
At the spring and autumn equinoxes, the sun's circuit is above the Equator line of the flat Earth disc — midway between the Tropic of Cancer and Tropic of Capricorn. From this central position, every point on Earth receives a roughly equal 12-hour day/night cycle, because the sun's visible arc above any observer's horizon covers approximately half its circuit. This is elegantly consistent with a local circular path over a flat disc — and requires no orbital mechanics or 23.5° tilt of a spinning globe to explain.
The Analemma — Evidence of the Spiral
If you photograph the sun at exactly the same clock time every day for a full year, the sun traces a figure-8 shape called the analemma. This figure-8 reflects the sun's changing north-south position (the vertical axis) and its changing east-west speed (the orbital eccentricity effect, the horizontal axis). On a flat Earth, the analemma is the direct photograph of the sun's annual spiral — a physical trace of its outward and inward circuit path over the year.
Midnight Sun Explained
The "midnight sun" — sunlight present at midnight in Arctic summer — is explained on the flat Earth by the sun's circuit being above the northern regions of the disc during June, where it never fully recedes past the horizon because it is circling close to the North Pole centre. The sun stays above the visible horizon from northern vantage points at all hours. On a globe, the midnight sun is explained by the axial tilt — both models make the same prediction for this phenomenon.